1. Field of the Invention
The present invention relates to an image forming apparatus and a method of controlling an image forming apparatus.
2. Description of the Related Art
Heretofore, an image forming apparatus is known in which forming an electrostatic latent image on a photosensitive element by optical writing and primarily transferring a toner image obtained by developing the electrostatic latent image to an intermediate transfer material such as an intermediate transfer belt are carried out for each color so that the toner images of the respective colors overlap each other on the intermediate transfer material, and then the toner images of the respective colors on the intermediate transfer material are transferred and fixed to a sheet to obtain a color image.
In this image forming apparatus, in carrying out image adjustment, such as color misregistration correction or density correction, on an image to be formed, in general, a test pattern is formed on the intermediate transfer belt and detected by a sensor. Meanwhile, at the time of the image adjustment, since normal image formation is not carried out on a sheet, if the image adjustment is frequently carried out, a downtime for which image formation on a sheet is interrupted increases, and efficient image formation may not be carried out.
In order to reduce the downtime, Japanese Patent Application Laid-open No. 2009-169031 describes a method in which a test pattern is formed in regions that are other than the image region on the intermediate transfer belt and are located at both sides of the image region to sandwich the image region, and image adjustment is carried out on the basis of a result of detecting the test pattern by a sensor. According to this method, it is possible to reduce the downtime of the apparatus by process control for image formation using a test pattern and to obtain stable image quality.
In Japanese Patent Application Laid-open No. 2009-169031, an elapsed time in which the test pattern is conveyed to a position of the sensor, the test pattern is detected by the sensor and an adjustment value is calculated on the basis of a result of detecting is not taken into consideration. For this reason, in order to reflect the adjustment value obtained by detecting the test pattern in a target image, a wasteful waiting time occurs.